U.S. patent application number 11/891287 was filed with the patent office on 2008-03-06 for distal targeting device.
This patent application is currently assigned to Stryker Trauma GmbH. Invention is credited to Robin Buscher, Ilan Howling, Stefan Voelzow.
Application Number | 20080058829 11/891287 |
Document ID | / |
Family ID | 38661676 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080058829 |
Kind Code |
A1 |
Buscher; Robin ; et
al. |
March 6, 2008 |
Distal targeting device
Abstract
A targeting device for targeting a cross bore in a bone nail has
an arm member coupled to an end portion of the bone nail and an
aiming portion forming part of the arm member extending parallel to
a longitudinal axis of the bone nail. An adjustable aiming device
is mounted on the aiming portion, the adjustable device having a
guide bore alignable with the cross bore in the nail. The
adjustable device is moveable with respect to the aiming portion in
a direction perpendicular to a plane containing both the nail
longitudinal axis and central axis of the cross bore. A target
indicator is mounted on the adjustable aiming device. The target
indicator has a radiolucent body including a planar portion having
spaced parallel radiopaque elements therein.
Inventors: |
Buscher; Robin; (Monkeberg,
DE) ; Voelzow; Stefan; (Monkeberg, DE) ;
Howling; Ilan; (Kiel, DE) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,;KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Assignee: |
Stryker Trauma GmbH
Schonkirchen
DE
|
Family ID: |
38661676 |
Appl. No.: |
11/891287 |
Filed: |
August 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11593996 |
Nov 7, 2006 |
|
|
|
11891287 |
Aug 9, 2007 |
|
|
|
60836793 |
Aug 10, 2006 |
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Current U.S.
Class: |
606/96 |
Current CPC
Class: |
A61B 17/1703 20130101;
A61B 17/72 20130101; A61B 17/1725 20130101 |
Class at
Publication: |
606/096 |
International
Class: |
A61B 17/58 20060101
A61B017/58 |
Claims
1. A targeting device for targeting a cross bore in a bone nail
comprising: an arm member capable of being coupled to an end
portion of a bone nail, wherein the arm member comprises an aiming
portion extending parallel to a longitudinal axis of the bone nail;
an adjustable aiming device mounted on the aiming portion, the
adjustable aiming device having a guide bore alignable with the
cross bore in the nail, the adjustable aiming device moveable with
respect to the aiming portion in a direction perpendicular to a
plane containing both the nail longitudinal axis and central axis
of the cross bore; and a target indicator mounted on the adjustable
aiming device, the target indicator having a radiolucent body
including first and second angled leg portions forming an apex at a
first end of each portion, the first leg portion having spaced
radiopaque elements therein.
2. The targeting device as set forth in claim 1 wherein the
adjustable aiming device is moveable in a longitudinal direction
along the portion of the arm member extending parallel to the bone
nail.
3. The targeting device as set forth in claim 1 wherein the first
leg portions include at least three spaced radiopaque elements.
4. The targeting device as set forth in claim 3 wherein a central
radiopaque element is thicker than at least two other radiopaque
elements.
5. The targeting device as set forth in claim 4 wherein the central
radiopaque element is a metal rod and the other radiopaque elements
are etched metal.
6. The targeting device as set forth in claim 5 wherein the at
least two other radiopaque elements are spaced at least 2.5 to 5 mm
increments above and below the central radiopaque element.
7. The targeting device as set forth in claim 5 wherein there are
at least four other radiopaque elements in combination with the
central radiopaque elements.
8. The targeting device as set forth in claim 7 wherein at least
two of the four radiopaque elements have lengths shorter than the
central and the other radiopaque elements.
9. The targeting device of claim 7 wherein all the radiopaque
elements lie in the same place.
10. The targeting device as set forth in claim 1 wherein the first
and second leg portions extend from the apex at an angle to one
another between 15 and 45.degree..
11. The targeting device as set forth in claim 10 wherein the
second leg portion includes one radiopaque pin element extending
with respect to the first leg of the angle formed at the apex there
between.
12. The targeting device as set forth in claim 5 wherein the angle
is 300.
13. The targeting device as set forth in claim 1 wherein the
adjustable aiming device is made of a radiolucent material.
14. A method for locating a cross bore in an intramedullary nail
comprising: inserting an intramedullary nail having a cross bore in
a bone canal; coupling a targeting arm to the intramedullary nail,
the targeting arm having a portion extending parallel to a
longitudinal axis of the nail; mounting an adjusting device having
a cross bore drill guide on the portion of the targeting arm
extending parallel to the nail longitudinal axis, the adjusting
device drill guide moveable in a direction perpendicular to a
central axis of the bore and the nail longitudinal axis, the
adjusting device having a target indicator coupled thereto having
at least three parallel radiopaque elements thereon; aligning the
target indicator in an x-ray beam with the nail cross bore; and
positioning the cross bore drill guide in alignment with the nail
cross bore by aligning the drill guide in the x-ray beam with a
central one of the parallel radiopaque elements, if necessary, by
moving the adjusting device.
15. The method as set forth in claim 14 wherein the target
indicator has first and second leg portions joined at an apex and
angled with respect to one another at between 15 and 45.degree.
16. The method as set forth in claim 15 wherein the first leg
portion has the at least three radiopaque elements therein.
17. The method as set forth in claim 16 wherein the second leg
includes a radiopaque alignment element extending along a
longitudinal axis thereof.
18. The method as set forth in claim 17 wherein the aligning of the
target indicator in the x-ray beam comprises aligning the second
leg radiopaque element coaxially with an axis of the x-ray
beam.
19. The method as set forth in claim 14 wherein two of the at least
three radiopaque elements are spaced from the central one of the
radiopaque elements by between 2.5 and 5 mm.
20. The method as set forth in claim 19 wherein the adjusting
device has indicators at 2.5 to 5 mm corresponding to the target
indicator first arm radiopaque element spacing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 11/593,996, filed on Nov. 7, 2006, and claims
the benefit of provisional Application No. 60/836,793 filed Aug.
10, 2006, the disclosures of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] In order to accurately lock long intramedullary nails (i.e.
those with distal attachment screws) the distal screws have to be
accurately aligned with the cross bores in the nail. This locking
is complicated by the deflection of the nail during insertion into
the bone canal which changes the location of the cross bore from
their static position. Typically the surgeon has been forced to do
this freehand with the help of an x-ray C-arm. A common problem in
such a procedure is that the instruments are "in the way" since
they are on the image plane of the C-arm. Furthermore, distal
locking is problematic since the distal bores cannot be made
precisely through the soft tissue due to the anatomical shape of
the femur and the resulting curvature of the nail (here in a Z
direction) which is in a plane perpendicular to a plane parallel to
the frontal plane.
[0003] Intramedullary nails often provide two distal openings or
cross bores for distal locking. For distal locking a nail may offer
three locking options to be used, depending on the fracture
pattern. To accomplish this a proximal round hole is provided and a
more distal oblong hole. Distal locking is recommended if the
fracture is unstable, if rotational stability is required or if
there is a wide disparity between the diameter of the nail and the
femoral cavity.
[0004] The first possibility is placing a locking screw in the
distal part of the oblong hole. This creates a dynamic locking
mechanism i.e. allows the nail to move distally and requires only
one screw. Alternatively, one screw may be placed in the distal
part of the oblong hole and the other in the round hole. This
causes a static locking of the nail and prevents movement of the
nail. However, if dynamization is required after a period of time,
the screw, placed in the round hole, may be removed leaving only
the screw at the distal end of the oblong bore. This method
requires two screws. Lastly, one screw may be placed in the round
hold and the other placed in the proximal part of the oblong hole.
Again this produces static locking and requires the placement of
two screws.
[0005] Various techniques can be used to guide drilling and
insertion of screws through the distal holes. The freehand
technique described above as well as targeting instruments such as
used in a straight on approach of the imaging device described
below.
[0006] The essential initial step in distal targeting is to
position the fluoroscope so that the circular distal hole in the
nail appears perfectly round. Naturally, this visualization cannot
be used with the oblong hole. If the round hole appears to be
elliptical in either the vertical or horizontal plane, the
fluoroscope image position must be adjusted appropriately. It is
advised to correct the image in one plane at a time.
[0007] Once an image intensifier is correctly positioned a tip of a
drill is placed at the center of the hole and a hole drilled
through the first cortex which in a femur is the lateral cortex and
the nail cross bore until resistance of the second cortex is felt.
The drill typically has a scale for measuring the required screw
length.
[0008] Alternatively, a hole can be drilled through the second
cortex while viewing the image. The required screw length can then
be read directly from the screw scale on the drill. If a tissue
protection sleeve is used around the drill, it has to be removed
for the measurement. It is also possible to measure the correct
screw length using a free hand screw gauge which can engage the
medial cortex outer surface when the nail is in the femur. This is
done after drilling through the second cortex by removing the drill
and advancing the small hook of the screw gauge through the holes
behind the medial cortex and read out the required locking screw
length.
[0009] Typically the distal locking screw, which is usually a 5 mm
screw, is inserted through the skin by using a screwdriver. The
screw head is advanced carefully until it is just in direct contact
with the cortex. Any targeting instrumentation used is then
removed.
SUMMARY OF THE INVENTION
[0010] The present invention is intended to make locating the
screws easier and more accurate. An aiming or targeting arm is
attached to a known nail-holding arm. In a preferred embodiment a
fixation bolt is used to hold a targeting apparatus including the
aiming arm in a bore of the nail-holding arm. A clamping device
with a hand locking mechanism may also be used to hold the
targeting apparatus in the nail holding arm. A radiolucent
adjusting device (adjustable in the Z direction) is slid on to the
aiming arm by means of a pin inserted in a corresponding opening in
the aiming or targeting arm and secured by turning a lever. On the
aiming arm there are a series of holes with each hole having a
number that corresponds to the respective nail lengths (and thus to
the corresponding location of the distal bores in each nail).
[0011] A radiolucent target indicator, which is slipped onto a
dovetail guide found on the adjusting device, is the system with
which the exact position located on the level of the holes in the
nail is found. This is preferably done by using an oblique x-ray.
This positioning is achieved by aligning two planes, lying one
behind the other on the target indicator, in parallel with respect
to the longitudinal axis of the nail. For this the ribs of the
target indicator, which are otherwise transparent to x-rays, have
x-ray markings. In the first plane, there are bead-like x-ray
strips, such as dashed wires. In the second plane uniform straight
(solid) wires are used so that in correct Z positioning, on the
x-ray image, only two pairs of lines at a distance from each other
(dashed-straight) are recognizable. The wires and strips are not
aligned in the Z direction (i.e. the solid wires are preferably
spaced apart further than the dashed wire so that each wires lies
in a different plane in the Z direction.
[0012] The x-ray images may appear, for example, as follows:
[0013] First the x-ray C-arm is aligned. The image is as below if
the angle alignment is incorrect. ##STR1##
[0014] Here x-ray C-arm is in correct alignment (median-lateral and
x/y-plane). ##STR2##
[0015] Lastly, the adjusting device is adjusted so the hole
position of the nail in the Z plane
[0016] In a correct Z position, the position of the bore is outside
the solid indicators and the Z position can then be readjusted with
the help of the adjusting screw of the adjusting device until the
solid wires straddle to the central axis of the distal bores in the
nail.
[0017] X-ray markers in radiolucent locating arms for target
devices are known from U.S. Pat. No. 6,036,696 as well as the
brochure entitled Gamma Long Nail R 2.0 Operative Technique P. 25
including illustrations. This oblique x-ray operative technique is
also known in its fundamental characteristics from an article by
Hans Granhead, A New Technique Of Distal Screw Insertion For Locked
Nailing, Acta Orthop Scan 1998 69(3): 320-321.
[0018] Advantageously, by means of the oblique C-arm method, a
freer access for the distal through-boring of the femur is achieved
and so the dangers of drilling under x-ray imaging are minimized.
The targeting apparatus of the present invention provides a novel
method of locating the cross bores in a bone nail.
[0019] In order to deliver reproducible results with the targeting
apparatus of the present invention the adjusting device can be
adjusted in the Z direction with an adjusting screw thread having
no play. This may be accomplished by using a cover mounted on the
main body of the adjusting device, an O-ring, the thickness of
which is slightly greater than the recess provided for it in the
body of the adjusting device. The cover is pressed on and the
adjusting screw is screwed into the threads in the body, so that
the elastic O-ring stretches the sides of the adjusting screw
against the sides of the thread and takes the play out of the
connection.
[0020] A plastic template or a guide plate is used by the operator
in the readjustment of the desired positioning in view of the type
of locking, i.e. static or dynamic position. For this the
corresponding template or guide plate (right or left nail) is
placed on the adjusting device preferably using a
click-mechanism.
[0021] The instruments of the present invention are designed to
facilitate minimally invasive surgery and reduce the operating room
(OR) time down to a minimum by the aid of using new instrumentation
and an optimized surgical technique.
[0022] The nails have a proximal diameter of 15.5 mm to help
minimize the incision length required for minimally invasive
surgery. Nevertheless, they offer the same biomechanical strength
and cut-out resistance. A major advantage of the instrument
platform of the present invention is that the instruments are
designed for a minimally invasive surgical technique and reduce OR
time to a minimum. The instruments are easy to use and easy to
clean and can be used with a variety of intramedullary nails.
[0023] The targeting device of the present invention offers the
competitive advantages of minimizing fluoroscopy time, helping to
avoid misdrilling and easy calibration for each type of Gamma3 long
nail. The targeting device is mainly made out of radiolucent carbon
fiber material to overcome the problem of x-ray artifacts. This
will help the surgeon in getting an optimal accurate surgical
result.
[0024] As used herein when referring to bones or other parts of the
body, the term "proximal" means close to the heart and the term
"distal" means more distant from the heart. The term "inferior"
means toward the feet and the term "superior" means toward the
head. The term "anterior" means toward the front part or the face
and the term "posterior" means toward the back of the body. The
term "medial" means toward the midline of the body and the term
"lateral" means away from the midline of the body.
[0025] The invention relates to a targeting device for targeting a
cross bore in a bone nail which includes an arm member coupled to
an end portion of a bone nail and an aiming portion forming part of
the arm member extending parallel to a longitudinal axis of the
bone nail. An adjustable aiming device mounted on the aiming
portion, the adjustable device having a guide bore alignable with
the cross bore in the nail. The adjustable device is moveable with
respect to the aiming portion in a direction perpendicular to a
plane containing both the nail longitudinal axis and central axis
of the cross bore. A target indicator mounted on the adjustable
aiming device. The target indicator has a radiolucent body
including first and second spaced parallel planar portions each
having a spaced radiopaque element therein. The adjustable aiming
device is moveable in a longitudinal direction along the portion of
the arm member extending parallel to the bone nail. Preferably, the
target indicator includes a pair of spaced radiopaque elements in
both the first and second planar portions. The radiopaque elements
in the first planar portion are preferably spaced closer to each
other than the radiopaque elements in the second planar portion. In
the preferred embodiment the first and second planar portions
extend perpendicular to a plane containing the central axis of the
nail cross bore and containing a longitudinal axis of the nail
adjacent the cross-bore. The adjustable aiming device is made of a
radiolucent material. The guide bore on the aiming device is formed
in part by a radiopaque template having a bore therein aligned with
the nail cross-bore, the template removably mounted on the
adjustable aiming device adjacent the guide bore. The nail includes
two cross-bores spaced along the longitudinal axis of the nail and
the adjustable aiming device and template have two bores alignable
with the two nail cross-bores. One of the cross bores in the nail
is elongated in the direction of the longitudinal axis of the nail.
In the preferred embodiment the aiming portion of the arm member
includes a series of bores along the length thereof for receiving a
support pin extending from the adjustable aiming device. The arm
member preferably has a connector element at an end thereof
opposite an end coupled to the bone nail, the connector for
releasably engaging the aiming portion. A method is provided for
locating a cross bore in an intramedullary nail which includes
inserting an intramedullary nail having a cross bore in a bone
canal, coupling a targeting arm to the intramedullary nail, the
targeting arm having a portion extending parallel to a longitudinal
axis of the nail, mounting an adjusting device having a cross bore
drill guide to a central axis of the bore and the nail longitudinal
axis, the adjusting device drill guide moveable in a direction
perpendicular on the portion of the targeting arm extending
parallel to the nail longitudinal axis, the adjusting device having
a target indicator coupled thereto having two sets of parallel
radiopaque elements thereon, aligning the two sets of parallel
radiopaque elements in an x-ray beam, and locating the cross bore
in the nail by centering the cross bore in the x-ray beam between
the two sets of parallel radiopaque elements if necessary by moving
the adjusting device. A distance between the first set of parallel
radiopaque elements is less than the distance between the second
set. Preferably the first set of radiopaque elements are solid pins
and the second set of radiopaque elements are a series of connected
bead elements. The locating of the plane parallel to the frontal
plane is accomplished by placing the solid pins within the series
of connected bead elements at the same spacing as on the target
indicator. The first set of radiopaque elements are solid pins and
the second set of radiopaque elements are a series of connected
bead elements.
[0026] Preferably a plane containing ends of the radiopaque
elements of the first and second sets of radiopaque elements forms
a non zero angle with a plane containing the first set of parallel
radiopaque elements and a plane containing the second set of
parallel radiopaque elements. A fracture fixation system is also
provided for a long bone comprising: a bone nail having at least
one cross bore and preferably a pair of cross bores therethrough.
An arm member is coupled to an end portion of the bone nail,
wherein the arm member comprises an aiming portion extending
parallel to a longitudinal axis of the bone nail. An adjustable
aiming device is mounted on the aiming portion. The adjustable
aiming device has a guide bore alignable with the cross bore in the
nail. The adjustable aiming device is moveable with respect to the
aiming portion in a direction perpendicular to a plane containing
both the nail longitudinal axis and central axis of the cross bore.
A target indicator is mounted on the adjustable aiming device, the
target indicator having a radiolucent body including first and
second spaced parallel planar portions each having a spaced
radiopaque element therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an elevation view of a typical intramedullary
fracture fixation nail for the femur having a pair of distal bone
screws extending through the cortex of a long bone;
[0028] FIG. 2 is an exploited isometric view of the targeting
apparatus of the present invention;
[0029] FIG. 3 is the targeting apparatus of FIG. 2 in the assembled
unlocked condition with the nail FIG. 1 inserted into a femur;
[0030] FIG. 4 is an isometric view of the targeting apparatus of
FIG. 3 in a locked condition;
[0031] FIG. 5 is the targeting apparatus of FIG. 4 just prior to
receiving an adjusting device being mounted thereon;
[0032] FIG. 6 is the targeting apparatus of FIG. 5 with the
adjusting device mounted thereon including a radiolucent tissue
protection sleeve in the adjusting device.
[0033] FIG. 7 is an exploited view of the adjusting device shown in
FIGS. 5 and 6;
[0034] FIG. 8 is an elevation view of a tissue protection sleeve
guide template for use with a right femur;
[0035] FIG. 9 is an enlarged view of a portion of the adjusting
device just prior to the template of FIG. 8 being mounted
thereon;
[0036] FIG. 9A is an elevation view showing the adjusting device
mounted on an end of the targeting apparatus with the bores in the
guide template aligned with the bores in the bone nail in with the
adjusting device in an unlocked position;
[0037] FIG. 10 is an identical view to FIG. 9a with the adjusting
device in a locked position;
[0038] FIG. 11 is a partial elevation view showing the adjusting
device prior to the holes in the guide template being aligned with
the cross bores in the bone nail in the Z direction;
[0039] FIG. 12 shows an isometric view of the entire targeting
apparatus including adjusting device with a radiolucent tissue
protection sleeve mounted therein;
[0040] FIG. 13 shows a pair of radiolucent trocars both long and
short and a pair of radiolucent tissue protection sleeves to
receive the long and short radiolucent trocars;
[0041] FIGS. 14 and 14A are elevation views of a radiolucent trocar
equipped with a radiopaque element in the tip of the trocar;
[0042] FIGS. 15A, 15B and 15C are views of the distal ends of three
bone nails, each having a pair of cross bores showing the location
of a bone screw when dynamic locking, secondary dynamization
locking or static locking is desired;
[0043] FIG. 16A and FIG. 16B show the targeting apparatus of the
present invention mounted on a bone nail inserted into the femur of
a patient located in a c arm X-ray machine which can be adjusted
both in an x-y plane parallel to a frontal plane of the body and in
a Z direction lying in a plane parallel to the sagittal plane of
the body;
[0044] FIGS. 17A through 17C show the process of aligning the
radiolucent trocar of FIG. 14 when mounted in the adjusting device
to locate a cross bore in the nail when using a straight on X-ray
beam approach;
[0045] FIG. 18 is a partial isometric view of the targeting
apparatus of the present invention including the adjusting device
with a drill guide and dull bit mounted therein for drilling a hole
in the bone surrounding the nail for insertion of a bone screw;
[0046] FIG. 19 shows the insertion of a bone screw through a
drilled bone and into a cross bore of a bone nail utilizing the
targeting apparatus and adjusting device of the present
invention;
[0047] FIG. 20 is an isometric view showing the insertion of a
second bone screw through a predrilled hole in the bone to a second
cross bore of the bone nail;
[0048] FIG. 21 shows the targeting apparatus of the present
invention including a target indicator to be used with an oblique
X-ray beam approach prior to the indicator being coupled to the
adjusting device of the present invention;
[0049] FIG. 22 is an isometric view of the target indicator showing
a spaced pair of dashed radiopaque wires mounted in the same plane
thereon;
[0050] FIG. 22A is an elevation view of the target indicator
showing the pair of dashed wires extending in the same vertical
plane and parallel;
[0051] FIG. 22B is a cross-sectional view of the target indicator
of FIG. 22A along line B-B rotated 90.degree. showing the co-planar
dash wires at the top and a pair of spaced solid radiopaque wires
at the bottom;
[0052] FIG. 23 is an isometric view showing the targeting apparatus
of the present invention including target indicator mounted on the
adjusting device with an X-ray beam extending at an oblique angle
therewith;
[0053] FIG. 24 shows in group A lines which would appear on a
fluoroscope when the X-ray beam is not aligned with the X-Y plane
of the nail cross bores and in Group B showing the dashed wire and
solid wire alignment when the X-ray beam is correctly aligned;
[0054] FIG. 25 shows the view on the fluoroscope when the center of
the cross bore is incorrectly aligned (wire group A) and when the
dashed and solid wires are correctly aligned about the center of
the cross bore (Group B);
[0055] FIG. 26 shows a partial view of the targeting apparatus of
the present invention including adjusting device with the target
indicator mounted thereon being adjusted in the Z direction to
correctly align the bores and the guide template with the cross
bores in the bone nail;
[0056] FIG. 27 is a fluoroscopic image of the correctly aligned
target indicators with the dashed and solid wires correctly aligned
with the cross bore in the bone nail;
[0057] FIG. 28 is an isometric view of the target apparatus
assembly including adjusting device and target indicator with a
tissue protection sleeve mounted thereon to guide a trocar and
forming an incision prior to drilling the bone for receipt of a
bone screw;
[0058] FIG. 29 is a view similar to FIG. 20 showing the insertion
of the second bone screw in a cross bore of a bone nail after the
bone has been dulled when using the oblique approach;
[0059] FIG. 30 is an isometric view of an alternate target
indicator of the present invention having first and second legs
oriented at an angle;
[0060] FIG. 31 is an elevation view of the target indicator of FIG.
30;
[0061] FIG. 32 is an elevation view of the first leg of the target
indicator shown in FIG. 31 along lines 32-32 thereof;
[0062] FIG. 33 is an elevation view of yet another embodiment of
the target indicator of the present invention similar to that shown
in FIG. 30 but with the first and second legs connected by a pivot
hinge;
[0063] FIG. 34 is an isometric view of the target indicator of FIG.
30 mounted on an adjustment device similar to that shown in FIGS.
7-9;
[0064] FIG. 35 is the targeting system of the present invention
including the target indicator of FIG. 30 in a simulated x-ray
beam;
[0065] FIG. 36 is a fluoroscopic view of a trocar to be aligned
with a distal hole in a nail utilizing the target indicating
elements of FIG. 32;
[0066] FIG. 37 is an intermediate fluoroscopic view of the trocar
and nail being aligned; and
[0067] FIG. 38 is a fluoroscopic view showing the metal trocar in
alignment with the distal nail hole of a bone nail.
DETAILED DESCRIPTION
[0068] Referring to FIG. 1, there is shown a typical intramedullary
nail 10 used for fracture fixation such as sold by Stryker Trauma
GmbH as a GAMMA.RTM. long bone nail. Nail 10, when used in a femur
12 includes a lag screw 14 for insertion into the head of a femur
and a pair of distal locking screws 17 going through bore 16 and
oblong hole 18, which engage the cortical bone on both the lateral
and medial sides of the distal femur 15.
[0069] Referring to FIG. 2, there is shown a partially assembled
targeting apparatus of the present invention generally denoted as
20, which includes a handle portion 22 coupled to proximal end 24
of femoral intramedullary nail 10. Handle 22 may be coupled by a
threaded connection to proximal end 24 of nail 10 or in any other
manner all of which are well-known in the art. In a preferred
embodiment, handle 22 includes a coupling portion 26, which is
adapted to receive various targeting apparatus for locating and
drilling the bone for receipt of the femoral lag screw 14 and the
distal bone screws bores 16 and 18. For example, such a targeting
arm for a lag screw may be similar to that shown in U.S. Pat. Nos.
6,039,739 and 7,077,847, the disclosures of which is incorporated
herein by reference. As shown in FIG. 2, the targeting apparatus 20
includes a distal targeting arm 28, which includes a mounting
system 30 adapted to be coupled to portion 26 of arm 22. Arm 26 is
provided with a series of through bores 32 for receiving a fixation
bolt 34. As will be discussed in more detail below, distal
targeting arm 28 includes an adjusting device 36 mounted
thereon.
[0070] Referring to FIG. 3, there is shown bone nail 18 inserted
into a right femur 12 with coupling apparatus 30 inserted on to
portion 26 of arm 22 just prior to inserting fixation bolt 34
through one of the bores 32 in portion 26. To ensure the correct
rotational alignment between coupling portion 30 and portion 26 of
arm 22, a window 38 may be provided in coupling portion 30 to
locate an alignment indicator formed on portion 26 (not shown). A
distal targeting arm lever 40 may be provided, which is coupled to
a locking member which fits within an internal bore of portion 26
such that when lever 40 is rotated, a tight frictional lock is
developed between handle portion 26 and coupling portion 30. This
lock position is shown in FIG. 4. obviously any method of coupling
targeting arm 28 to handle 22 may be used. It would even be
possible to make the entire targeting apparatus in one piece. After
the distal targeting arm is mounted to handle 22, it is located
outside the body in generally parallel alignment to the
longitudinal axis of nail 18.
[0071] Referring to FIGS. 5 and 6, there is shown adjusting device
36 immediately prior to its mounting on distal targeting arm 28.
Adjusting device 36 is mounted in one of a series of bores 42 on
distal targeting arm 28. Each of the bores 42 locates the adjusting
device 36 in correct alignment for one of a series of different
length bone nails. Obviously the shorter the nail, a bore 42 closer
to the proximal end of nail 18 is used. When mounted in the proper
hole 42 for a given length nail, the adjusting device is in
alignment with the cross bores 16 and 18 at the distal end of the
nail 10. It should be noted that both arm 28 and adjusting device
36 are made of a radiolucent material such as PEEK
(polyetheretherketone).
[0072] Referring to FIG. 7 there is shown an exploded view of the
adjusting device 36. Device 36 includes a pair of adjustable
members 50 and 52 which can be moved up and down within a cavity 54
in a body 56 of device 36. A coupling pin 58 extends through
members 50 and 52 and therefore moves vertically within cavity 54
upon actuation of an adjusting screw 60. Pin 58 includes a pair of
radially extending tabs 62 and 64, which are received within
slotted recesses 43, 45 which open into bores 42 of arm 28. (See
FIG. 9A.) Tabs 62 and 64 prevent rotation of pin 58 after insertion
into bore 42. Also mounted in body 56 are a pair of support pins 66
and 68, which are used to mount a template shown in FIG. 8. A
locking mechanism generally denoted as 70 is provided which is
capable of locking moveable elements 50 and 52 and therefore pin 58
in a desired vertical position within cavity 54 of body 56. Thus,
when assembled and when pin 58 is mounted in bores 42 of adjusting
arm 28, the adjusting device body 56 may be moved up and down in
the Z direction by the rotation of screw 60. In the preferred
embodiment screw 60 is designed to have no play so that accurate
adjustments can be made. This may be accomplished with an o-ring 67
and cover 69 which forces the o-ring against shaft 73 of screw 60.
Body 56 includes a pair of dovetail shaped extensions 91, 92 on
each side surface. When a desired location is reached, the locking
mechanism 70 may be actuated by turning lever 71 to lock the body
56 with respect to pin 58. Obviously, there are many other ways to
design the adjusting device. However, what is essential is that the
adjusting device body 56 may move relative to pin 58, at least in
the Z direction, after being mounted on arm 28.
[0073] Referring to FIG. 8, there is shown a right template 74 to
be used with the adjusting device 36. Template 74 includes a pair
of mounting openings 76 and 78 and a pair of bores 82 for use in
locating the cross bores in the bone nail, guiding a drill for
drilling cortical bone adjacent the cross bores and for inserting
bone screws in the cross bores. While a template 74 for a right
femur is shown the template for the left femur would be similar
with holes 80 and 82 ("dynamic" and "static") reversed. The
"static" and "dynamic" markings refer to the location of the bone
screws in circular bores 16 and oblong bore 18 as discussed below.
Template 74 includes openings 76 and 78 for mounting the template
on the pins 66 and 68 of adjusting device 36. Since template 74 is
made of plastic, one way to provide left and right template 74 is
to mold the necessary markings for the right template on one side
and the markings for the left template on the other side.
[0074] Referring to FIG. 9, there is shown right template 74 just
prior to being mounted on pins 66 and 68 of the adjusting device.
As can be seen in FIG. 9, pins 66 and 68 are generally cylindrical
but have recess portions 69 for receiving upper flat surfaces 84
and 86 of opening 76 and 78. Thus, template 74 is located on pins
66 and 68 and then slid downwardly in FIG. 9 to lock template 74 on
the adjusting device. It should be noted that adjusting device 36
has oblong bores 88 and 90 so that different spacings between bores
80 and 82 of template 74 can be accommodated. This would be
required when secondary dynamization is required.
[0075] FIG. 9A shows the adjusting device 36 mounted on arm 28 with
the bores 80 and 82 aligned with circular bore 16 and the proximal
end of oblong bore 18 of nail 10. In the position shown in FIG. 9A
locking system 70 is in the unlocked position. Referring to FIG.
10, lever 71 of locking system 70 is moved to the locked position
thereby fixing the adjusting device 36 and template 74 in the
desired position. Also shown in FIGS. 9A and 10 are the pair of
dovetail-shaped mounting elements 91 and 92 formed on the sides of
body 56 of adjusting device 36. The function of these
dovetail-shaped elements 91 and 92 will be discussed in more detail
below.
[0076] Referring to FIG. 11, in contrast to FIGS. 9A and 10,
adjusting device 36 is shown in an incorrect position in the Z
direction, whereby the surgeon must adjust the template position by
turning screw 60 to thereby move body 56 of adjusting device 36
until correct alignment is achieved. It should be noted that the
template 74 in FIG. 11 in a left template has holes 80 and 82
located closer together than that shown in the right template 74 of
FIG. 8, which allows the bone screw being inserted in oblong hole
18 to be at the proximal most portion of the oblong hole 18 whereas
the template of FIG. 8 has a wider spacing so that the bone screw
will be located at the distal most end of oblong hole 18. The
closer hole location on template 74 will produce static locking
whether the template is a right or a left template. This is best
shown in FIG. 15 wherein the right most nail 100 shows the bone
screws are positioned for static locking to prevent the nail from
moving distally within the medullary canal. The central FIG. 102 is
referred to as secondary dynamization in which the nail can move
distally if the bone screw in round cross bore 16 is removed.
Dynamic locking is shown in nail section 104 in which the nail may
move distally about the single cross-locking screw in oblong hole
18. The spacing between the two screws is greater in nail 102
versus nail 100 so that two different left and right templates 74
are required.
[0077] Referring to FIG. 12, there is shown the targeting apparatus
with adjusting device 36 mounted thereon including a radiolucent
tissue protection sleeve 106 mounted within hole 82 of template 74.
A tissue protection sleeve helps guide a trocar and a drill into
alignment with the cross bore in the distal end of nail 10 and
protects the tissue when drilling through the cortical bone of the
distal femur.
[0078] Referring to FIG. 13, there is shown long and short
radiolucent trocars 110 and 112, respectively, and long and short
radiolucent tissue protection sleeves, 114 and 116, respectively.
Tissue protection sleeves 114 and 116 are tubular with a bore there
through for accommodating the radiolucent standard trocar for
cutting tissue and a drill bit for drilling a hole in the cortical
bone of the femur. Both long and short trocars and sleeves are
provided to accommodate different size patients. However, use of
the short trocar is preferred since there will be less angular
error between the support on the adjusting device 36 and the end of
the sleeve.
[0079] Referring to FIG. 14, there is shown long radiolucent trocar
110 which has a tip 118 including a radiopaque element 120 along
its central axis 122. The short radiolucent trocar has the
identical tip structure including radiopaque target member 120. The
radiolucent trocars are used for targeting the cross bores in the
nail as will be discussed below in connection with the straight on
x-ray beam approach. As discussed above, the short sleeve is
preferred. The tissue protection sleeves 114 and 116 need to be of
a sufficient length to contact the cortical surface of the bone to
thereby protect the tissue during the drilling operation.
[0080] Referring to FIGS. 16A and B, there is shown the use of a
standard adjustable x-ray imaging device in a straight on approach
with a patient's leg inserted in the x-ray beam path. The targeting
apparatus 20 of the present invention is mounted on a nail which
has been inserted into the medullary canal of, in the case of FIGS.
16A and 16B, the left femur. The figures show the movement of the
imaging device to align the fluoroscope 124. The essential initial
step in distal targeting is to position the fluoroscope image so
that the distal hole 16 in the nail appears perfectly round.
Naturally, this visualization step refers to the appearance of the
round hole and not the oblong hole 18. If the hole appears to be
elliptical in either the vertical or horizontal plane, the image
intensifier position must be adjusted appropriately as shown in the
schematic diagrams in FIGS. 16A and 16B. It is advised to correct
image in one plane at a time. Radiolucent trocar 110, 112 is
equipped with a radiopaque element in the tip of the trocar. This
helps to determine the exact position of the trocar in the straight
on approach. FIGS. 17A through 17B show the use of the radiolucent
trocars, either 110 or 112, to locate the bore 16 in the straight
on x-ray beam approach. FIGS. 17a through 17c are the fluoroscope
images seen by the surgeon with the properly located radiolucent
trocar shown in FIG. 17c.
[0081] Referring to FIG. 18, there is shown the targeting arm 28
with the adjusting device 36 mounted thereon in the locked position
with long sleeve 130 mounted in hole 82 of a left template to guide
a drill 132 through the cortical bone on the lateral side of the
femur, through the cross bore 16 of nail 10 and through the
cortical bone on the medial side of the femur.
[0082] Referring to FIG. 19, there is shown the insertion of a
first bone screw 136 through bore 80 of a left template and into
the oblong cross bore 18 of bone nail 10. This of course is
accomplished after cross bore 18 has been drilled in a similar
manner as to that shown in FIG. 18.
[0083] Referring to FIG. 20, there is shown a second bone screw 138
being inserted through cross bore 16 of bone nail 10 in a manner
similar to that of bone screw 136. Both bone screws are inserted
with a standard screwdriver 140 and 142, respectively. For ease of
use handle 146 of screwdriver 140 may be removed so that handle 148
of screwdriver 142 may be more accessible. Since two bone screws
are being used, per FIG. 15 either static locking or secondary
dynamization is being used (depending on which end of oblong bore
18 receives the screw).
[0084] FIGS. 21 through 29 show the use of the targeting apparatus
20 when used with the preferred oblique approach. The oblique
approach is preferred because by orienting the x-ray beam at an
angle of between 20.degree. and 45.degree. and preferably
30.degree. to the longitudinal axis of bone nail 10, the actuation
of screwdrivers 140, 142 via handles 146, 148 can take place by
hand outside the x-ray beam. In order to align the adjusting device
36 and therefore holes 80, 82 with the bores 16 and 18 of the nail
10, a target indicator 150 is used. In the preferred embodiment, as
shown in FIGS. 22, 22a, and 22b, indicator 150 is made of a
predominantly radiolucent material such as PEEK and is in the shape
of a parallelepiped. In the preferred embodiment a 30 degree angled
parallelogram design was chosen for indicator 150 due to the
operative technique. The angle of the indicator frame is canted 30
degrees from the perpendicular so that when the surgeon places the
C-arm in angle of 40 or 20 degrees for anatomical reasons
(sometimes the patient's other leg is in the way so the angle has
to be rearranged) he or she sees none of the radiopaque markers. If
a rectangular design (0 degrees from perpendicular) was used it
would significantly "lose" usable radiopaque indicator length
during the oblique alignment procedure. Indicator 15 has four legs
152, 154, 156, and 158, respectively. Legs 154 and 156 lie in a
first plane parallel to a plane containing legs 152 and 158.
Likewise, legs 152 and 154 are co-planer with a plane which is
parallel to the plane containing legs 156 and 158. The legs 154 and
156 are connected by side legs 155 and 157 which, as described
above, are angled at 30 degrees. Likewise legs 152 and 158 are
connected by side legs 159 and 161. In the preferred embodiment, as
can be seen in FIG. 22A legs 152 and 154, while being composed
mainly of a radiolucent material, contain a radiopaque dashed or
beaded wire 160. In the preferred embodiment the dashed or beaded
wire 160 is molded into arms 152 and 154 during the manufacture of
target indicator 150. As best seen in FIG. 22b legs 156 and 158
contain solid radiopaque wires 162 which are also preferably molded
in place during manufacture of target indicator 150. As seen in
FIG. 22b the spacing between solid wires 162 is less than the
spacing between the dashed or beaded wires 160. Thus the different
wires 160 and 162 can be easily distinguished in a fluoroscopic
image showing two dashed lines and two solid lines. Of course the
solid wires and dashed wires could be reversed without changing
their function i.e. legs 156 and 158 could have the dashed wires 16
and legs 152 and 154 could have the solid wires.
[0085] In the preferred embodiment target indicator 150 has a
dovetail-shape recess 164 best shown in FIG. 21 for engaging the
male dovetail-shaped side extensions 90 and 92 of body 56 of
adjusting device 36. Referring to FIG. 10 when the right femur is
being addressed target indicator 150 is mounted on male dovetail
extension 92 and when the left femur is addressed extension 90 is
utilized for mounting target indicator 150. In both cases target
indicator 150 extends from adjusting device 36 toward the proximal
end of nail 10.
[0086] Referring to FIG. 23, there is shown targeting apparatus 20
mounted on a left femur with target indicator 150 mounted on
dovetail 90 of adjusting device 36. The fluoroscope machine 124 is
shown as being oriented at an angle of about 30.degree. to the
longitudinal axis of nail 10. It can be seen that in this position
the x-ray beam 170 is offset from the axis through which the bone
screws are inserted into the distal femur and bores 16 and 18 and
thus the hands of the surgeon would not enter the x-ray beam.
[0087] Referring to FIG. 24, there is shown the alignment method
for determining the correct location of the nail cross bores 16 and
18 using the target indicator 150. In the image group of four lines
labeled "A" it can be seen that the dashed wire 160 in the upper
leg 154 and lower leg 152 are positioned above and below the solid
wire 162 of leg 156 with solid wire 162 of arm 158 located below
both dashed wires 160. This means the x-ray beam is not coplanar
with the x-y plane of the cross bores 16, 18 of nail 10. However,
when proper alignment is achieved the grouping of lines shown in
Group B of FIG. 24 now coincides with the correct alignment and
spacing shown in FIG. 22b. Thus solid wires 162 are located between
both dashed wires 160.
[0088] Referring to FIG. 25, there is shown the use of adjusting
device 36 and therefore target indicator 150 to locate the now
aligned solid and dashed wires 160, 162 (group "B" of FIG. 24) with
the center of the distal end of slotted or oblong opening 18 of
nail 10. Group "A" of wires of 160, 162 show the incorrectly
located center of cross bore 18 with Group "B" showing the
correctly located center of cross bore 18. This is accomplished by
adjusting screw 60 of adjusting device 36 in the direction of arrow
"D" of FIG. 25. This process is shown for the left nail in FIG. 26
with the rotation arrows at the top of the figure indicating the
turning of screw 60 to adjust the template 74 (in this case a left
template 74) in the Z direction.
[0089] Referring to FIG. 27, there is shown the fluoroscopic image
viewed by the surgeon when the correct alignment as shown in FIG.
25 "B" is achieved. The bore 18 is located midway between solid
wires 162 by use of adjusting screw 60.
[0090] Referring to FIG. 28, there is shown the tissue protection
sleeve 114, 116 inserted through hole 80 of left template 74. The
holes in the cortical bone are then drilled as discussed above with
regard to the straight approach for both cross bore 18 and cross
bore 16. Likewise the bone screws are inserted as shown in FIG. 29
in the same manner as accomplished with the straight approach.
[0091] The operative technique will now be described for using both
the straight on and oblique approaches.
[0092] In the straight on approach after assembly of the targeting
apparatus 20 and insertion of nail 10 the appropriate locking
template 74 is brought over the template fixation pins 66, 68 and
fixed by pushing the locking template down onto the pins.
[0093] Two different templates 74 are available. One for the
static/static mode (right and left) and one for the static/dynamic
mode. As described this can be accomplished by having template 44
used on one side the left nail and on the other side for the right
nail.
[0094] The positioning pin 58 of the adjusting device is inserted
in the bore 42 of arm 28 and is fixed by turning lever 71
clockwise.
[0095] The length of the required nail determines the position of
adjusting device 36 on distal targeting arm 28. The nail lengths
are preferably marked on the distal targeting arm above the
appropriate hole 42.
[0096] The adjusting device is calibrated with the targeting device
assembled to the nail prior to insertion into the bore canal.
[0097] This can be done on a table in the OR. The calibration
places the adjusting device in the correct position for drilling
cross bore 16, 18 with the nail in a non-deflected state. Thus once
inserted the deflection will cause the bores 16, 18 to move only a
small amount from the calibration position. The longer drill is
assembled into the longer radiolucent tissue protection sleeve to
insure the nail is reached.
[0098] The assembly is brought to proximal hole 16 first. Now the
alignment is checked with a drill to see if the nail hole is hit
directly without any resistance. The drill must go through the nail
hole smooth and easily. If not, then the screw 60 is turned until
there is an easy and smooth access through the nail hole. When the
proximal hole is calibrated then the calibration is repeated with
the distal hole. This would be the correct medial-lateral position
of adjusting device 36 if no bending occurs during insertion of the
nail.
[0099] Calibration is done with the proximal nail hole first. This
is done because it is not necessary for the adjusting device 36 to
be exactly in the neutral position. This is because the proximal
distal nail hole is likely to deflect less on nail insertion.
[0100] After the calibration is made, the tissue protection sleeve
is withdrawn first followed by the drill sleeve and finally the
drill. Then distal targeting arm coupling 30 can be released by
moving lever 40 and fixation bolt 34 is removed. The distal
targeting device assembly is detached and the fixation bolt may be
put into a fixation bolt storage place molded on the distal
targeting arm 28.
[0101] The adjusting device is not removed from the distal
targeting arm to avoid misdrilling.
[0102] A straight approach may be used although not preferred. In
this approach the x-ray beam is in line with bores 16 and 18 and
perpendicular to the nail 10.
[0103] The distal targeting arm 28 with the adjustable device 36
still assembled is coupled to the handle 22 via coupling device
30.
[0104] A radiolucent trocar 110 or 112 is assembled into the
corresponding radiolucent tissue protection sleeve 114 or 116 and
pushed through the distal locking hole 80 in template 74 on
adjusting device 36 to the skin.
[0105] As shown in FIGS. 17A and 17B the x-ray view of the round
and oblong distal holes are incorrectly aligned. FIG. 17C shows the
x-ray beam correctly aligned in the Z plane.
[0106] Radiolucent trocar 110 or 112 is equipped with a radiopaque
element 120 in tip 118 of the trocar. This radiopaque element can
be used to determinate the exact position of the trocar tip in the
straight approach.
[0107] This feature is used to provide an optimal lateral alignment
of the tissue protection sleeves with the hole in the nail under
X-ray control by turning the screw 40 of the adjusting device 36.
When a proper medial-lateral (Z-plane) alignment is achieved, a
radiopaque dot produced by element 120 is centered (see FIG. 17C)
then the radiolucent trocar is replaced with a guide sleeve and
standard metal trocar.
[0108] A small incision is started at the tip of the standard
trocar, and is extended down to the lateral cortex of the distal
femur. The trocar will typically extend back of the sleeve by
approximately 3 mm when the tissue protection sleeve has reached
the lateral cortex. The tissue protection sleeve should be in good
contact to the bone (FIG. 6).
[0109] A second x-ray control should be performed to make sure that
the alignment is still correct. If necessary an adjustment is
performed by turning the knob of the adjusting device until a
proper alignment is achieved.
[0110] The screw length can be determined by any known method. For
example, the trocar is removed and replaced by calibrated 4.2
mm.times.340 mm drill. The surgeon drills through the first cortex
and, as the second cortex is reached, reads off the measurement on
a drill scale on the drill. The thickness of the cortex, which is
approximately 5 mm, is added to this measurement to select the
correct screw length.
[0111] Alternatively, the drill can be drilled through the second
cortex and monitored by x-ray or fluoroscope image. The screw
length can then be read directly from the scale on the drill.
[0112] The second cortex is then drilled. It is also possible to
measure the correct screw length using a known screw gauge after
drilling through the second cortex. The drill guide sleeve must be
removed and the screw gauge may be advanced through the tissue
protection sleeve. The small hook of the gauge is placed behind the
medial cortex and the required locking screw length is read from
the scale on the gauge.
[0113] The insertion of the screw is done in a standard manner as
in the straight on approach as described above by use of a
screwdriver through the tissue protection sleeve. The distal most
hole is addressed first. Preferably a 5 mm locking screw is
inserted through the distal end of radiolucent tissue protection
sleeve by using the screwdriver until a mark on the screwdriver
shaft approaches the distal radiolucent tissue protection sleeve
114 or 116. The screw head is advanced carefully until it is
lightly in direct contact with the cortex.
[0114] When a mark on the screwdriver shaft reaches the tissue
protection sleeve, this indicates that the screw head is near the
cortex. Care should be taken not to overscrew. The screw head
should come just into contact with the cortex and resistance should
be felt.
[0115] Preferably, the screwdriver shaft is left inside the tissue
protection sleeve. The screwdriver tip is left engaged in the first
screw head and the tissue protection sleeve is pushed over the
screw head, against the cortex. This helps ensure the stability of
the system. The screwdriver shaft helps keep the targeting arm in
position. Next, the most proximal hole is addressed.
[0116] Radiolucent trocar 110, 112 is assembled into the
radiolucent tissue protection sleeve 114, 116 and pushed through
the proximal locking hole in the adjusting device to the skin.
[0117] The same operative technique as described above for the most
distal hole is followed and the distal screw length measurement is
done in the same way as described above.
[0118] The drill sleeve is removed and the selected 5 mm fully
threaded screw is inserted with the screwdriver.
[0119] The targeting device can now be removed by removing the
screwdrivers/sleeves and opening lever 40 of the distal targeting
arm. Fixation bolt 34 is then withdrawn.
[0120] In the preferred oblique approach as described above, the
x-ray beam is oriented approximately 20.degree. to 45.degree.
oblique to the distal locking sleeves and oblique to the nail. This
offers the benefit, that during drilling, the drill tip can be seen
but the image intensifier is not in the axis of the power tool and
the drill.
[0121] After the calibration described above the distal targeting
arm 28 with still assembled adjusting device 36 is pushed over the
portion 26 of handle 20 until the spring detent is felt. In the
alignment indicator window 38 the white line 39 on handle portion
26 can be seen. Fixation bolt 34 is then inserted into the bore
until the click is felt and the targeting arm lever 40 is locked.
The target indicator 150 is then attached over the proximal
dovetail-shaped flutes 90, 92 (depending on right or left) of
adjusting device 36.
[0122] The essential initial step in distal targeting with the
oblique approach is to position the image intensifier approximately
20.degree. to 45.degree. and preferably 30.degree. oblique to the
distal locking sleeves and oblique to the nail.
[0123] To produce an optimal lateral alignment of the hole 16 or 18
in the nail under x-ray control, the c-arm of the x-ray machine is
positioned in a way that the nail shaft is in the middle between
the dashed wires and the solid wires of target indicator 150 as
discussed above.
[0124] Now the adjustment is performed by turning knob 40 of
adjusting device 36. A proper alignment is achieved when the
locking hole is midway between the dashed and solid wires as shown
in FIG. 27. The drilling and screw insertion is then performed as
in the straight insertion as described above.
[0125] While in the oblique approach it is not necessary to use
radiolucent trocars 110, 112. They could be used to further
indicate the location of cross bores 16 or 18 in nail 10. The image
on the fluoroscope would shown a line produced by radiopaque marker
12 rather than a circular dot as in the straight on approach.
[0126] Referring to FIGS. 30 and 31 there is shown an alternate
target indicator generally denoted as 200. Target indicator 200
includes a first leg 202 and a second leg 204. The legs are
connected at an apex end 206. Target indicator 200 has a dove tail
connection groove 208 for engaging dove tails 90, 92 of adjusting
device 36. Target indicator 200 is preferably made mainly of a
radiolucent material such as PEEK.
[0127] Then referring to FIGS. 30-32 first arm 202 which is made of
PEEK includes a series of radiopaque lines formed therein. In the
preferred embodiment the central line 210 is a metal pin having a
diameter greater than any of the other metal or radiopaque lines
212 which are formed on either side of the central line or pin
210.
[0128] Referring to FIG. 32 there is shown a top view of the first
arm 202 including larger central rod 210 and a series of long and
short thin radiopaque lines 212 having different lengths. The arm
has a plurality of short length radiopaque lines or elements 214
and a series of longer radiopaque lines or elements 216. In the
third embodiment there are three long and three short thin elements
or lines 214, 216 on each side (above and below in FIG. 32) central
pin 210. In the preferred embodiment the shorter lines 214 are
spaced at 2.5 mm increments with respect to the center of the line
of the pin 210 and with respect to the long lines 216. In a
preferred embodiment lines 216 are spaced at 5 mm with one shorter
line 214 located at 2.5 mm from each adjacent line 216. Thus, as
shown in FIG. 32, the three long radiopaque elements or radiopaque
lines 216 are spaced a maximum of 15 mm from a center line 211 of
radiopaque pin 210. In the preferred embodiment the thin lines 214,
216 within the first leg 202 are formed by an etching process
comparable to a method that is used in manufacturing circuit boards
in the electronics industry. In the preferred embodiment the etched
metal grid is then embedded into the radiolucent (plastic) material
in a "sandwich" fashion. In the preferred embodiment the angle
formed by the first and second legs at apex 206 is preferably
30.degree.. This angle is chosen to keep the surgeon's hand out of
the x-ray beam or fluoroscope during use. The angle between the
first and second legs can vary between 15 and 60.degree. and still
allow the surgeon's hands to be outside of the x-ray beam during
use.
[0129] Referring to FIG. 33, there is shown a second embodiment of
the target indicator shown in FIGS. 31-32. This target indicator
includes a pivot pin 220 which allows first leg 202A to pivot with
respect to second leg 204A to form an angle between 15.degree. and
60.degree.. A detent system (not shown) can be utilized to lock the
desired angle between the first and second arms. The target
indicator 200A is otherwise identical to that shown in FIGS. 30-32
and functions in an identical manner once the angle is set.
[0130] Referring to FIG. 34 there is shown the targeting system of
the present invention with the target indicator of FIGS. 30-34
mounted on an adjusting element 36 as described above with regard
to target indicator 150. The target indicator is adjusted in an
identical way with respect to the bores in the distal end of the
implant, for example, a femoral nail. The only difference is that
an alignment pin 222 is placed at the end of the second leg 204 so
that it may be aligned with the beam of x-ray machine 224 shown in
FIG. 35. The pin 222 appears as a dot when the beam is aligned with
second leg 204.
[0131] The method for using the alternate and preferred target
indicator is to attach the target indicator 200 to one of the two
dovetail-shaped mounting elements 91, 92 on the adjusting device 36
(depending on whether it is mounted on a right or left femur). A
metal trocar 240 is placed in the proximal hole of adjusting device
36, and k-wire or alignment pin 222 is inserted into the bore at
the end of the alignment arm in order to adjust the C-arm of the
x-ray machine. The trocar 240 may be housed within the tissue
protection sleeve 130. The C-arm is aligned so that the x-ray beam
is in line with the second leg 204 and at an oblique angle with
respect to the nail 12. A first x-ray shot is taken, and the
central thicker metal pin 210 shows the theoretical position of the
tissue protection sleeve 130 housing the metal trocar.
[0132] FIG. 36 shows how a first x-ray could look with the pointed
tip 242 of metal trocar 240 misaligned with the central thicker
metal bar on the scale. The C-arm of the x-ray machine would have
to be, again, aligned so that the metal tip of the trocar 240 lies
in line with the thicker central metal pin 210. Such an alignment
is shown in FIG. 37. There then exists a two-line (216) offset
between the tip of the metal trocar and the central axis of the
bore in the nail 12. Since the long lines 216 of the scale are
spaced at 5 mm, the offset would be approximately 10 mm since the
central axis of the distal nail hole is aligned with the second
line below the axis of the thicker metal bar. As indicated above,
the shorter etched lines 214 are spacer 2.5 mm, i.e., half-way
between each pair of long lines 216. Obviously, other scale
distances, either above and below the central thicker metal pin
210, are possible. These center-line offsets may result from the
deformation of the bone nail during insertion. In any case, from
the x-ray scan it can be seen whether the metal pin 210 is above or
below the distal nail hole, and the distance between the two. The
adjusting device 36 is adjusted to fully align the tissue
protection sleeve and the trocar center with the distal nail hole
(see FIG. 38). As shown in FIG. 38, the tissue protection sleeve
130 is fully aligned with the nail, and the drilling of the distal
hole can begin. The hole is drilled in a conventional manner as
described above.
[0133] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *